The present invention relates, in general, to the manufacture of individual disposable shoe covers. More particularly, the present invention pertains to a method and apparatus for the continuous and substantially automatic manufacture of such shoe covers.
U.S Pat. No. 4,304,021, the disclosure of which is hereby incorporated by reference herein, illustrates an apparatus for making disposable shoe covers in which two sheets or webs of material are drawn from two supply sources, e.g., two supply reels. An adhesive, such as, for example, a pressure sensitive hot melt glue, is applied to at least one of the webs at discrete intervals along the length of the web. The webs are then pressed together at a pressing station. This pressing produces adhesively joined segments at discrete intervals along the length of the webs. Following pressing, the lateral edges of the webs are sewn together. One lateral edge is sewn continuously from one adhesively joined segment to the next adhesively joined segment. However, the other lateral edge is sewn for only a portion of the distance between adjacent adhesively joined segments, which provides an access opening for an individual's shoe. Next, the webs are severed at the adhesively joined segments to form individual shoe covers. The toe and the heel of each shoe cover are joined with an adhesive, while the bottom and the top, except for the access opening, are sewn together.
Shoe covers made using some nonwoven fabric materials may be less durable than desired. Specifically, if the material for a web has two or more layers, or acts as if it has two or more layers, a shear force on the web of sufficient magnitude may cause the layers of the web to separate. If a shoe cover is made from two webs of this type of material, such a shear force may cause the outer layer of one or both webs to separate from the inner layer. The adhesive may still hold the inner layers together, but the shoe cover will, nevertheless, be damaged and unusable. In particular, certain variations of a material made especially for shoe covers and sold under the trademark "TYVEK" act as if they have two layers. This material effectively has two layers because, during manufacture, heat is applied to the outer surfaces of the fabric in such a manner that the outer surfaces become harder than the fibrous section between them. The harder outer surfaces act as the two layers, while the fibrous section between them acts as a connector. This material is susceptible to failure if a shear force of sufficient magnitude is applied, as described above.
Accordingly, a need exists for a method and an apparatus for manufacturing durable shoe covers from material that has two or more layers or acts as if it has two or more layers.